Hemodynamic Effect of Myocardial Bridging

Impact of Myocardial Bridge on Life‐Threatening Ventricular Arrhythmia in Patients With Implantable Cardioverter Defibrillator

Background

Myocardial bridge (MB), common anatomic variant, is generally considered benign, while previous studies have shown associations between MB and various cardiovascular pathologies. This study aimed to investigate for the first time possible impact of MB on long‐term outcomes in patients with implantable cardioverter defibrillator, focusing on life‐threatening ventricular arrhythmia (LTVA).

Methods and Results

This retrospective analysis included 140 patients with implantable cardioverter defibrillator implantation for primary (n=23) or secondary (n=117) prevention of sudden cardiac death. Angiographically apparent MB was identified on coronary angiography as systolic milking appearance with significant arterial compression. The primary end point was the first episode(s) of LTVA defined as appropriate implantable cardioverter defibrillator treatments (antitachyarrhythmia pacing and/or shock) or sudden cardiac death, assessed for a median of 4.5 (2.2–7.1) years. During the follow‐up period, LTVA occurred in 37.9% of patients. Angiographically apparent MB was present in 22.1% of patients; this group showed younger age, lower rates of coronary risk factors and ischemic cardiomyopathy, higher prevalence of vasospastic angina and greater left ventricular ejection fraction compared with those without. Despite its lower risk profiles above, Kaplan–Meier analysis revealed significantly lower event‐free rates in patients with versus without angiographically apparent MB. In multivariate analysis, presence of angiographically apparent MB was independently associated with LTVA (hazard ratio, 4.24; 95% CI, 2.39–7.55; P <0.0001).

Conclusions

Angiographically apparent MB was the independent determinant of LTVA in patients with implantable cardioverter defibrillator. Although further studies will need to confirm our findings, assessment of MB appears to enhance identification of high‐risk patients who may benefit from closer follow‐up and targeted therapies.

Accuracy of a novel stress echocardiography pattern for myocardial bridging in patients with angina and no obstructive coronary artery disease - A retrospective and prospective cohort study

BACKGROUND

Myocardial bridge (MB) may cause angina in patients with no obstructive coronary artery disease (CAD). We previously reported a novel stress echocardiography (SE) pattern of focal septal buckling with apical sparing in the end-systolic to early-diastolic phase that is associated with the presence of an MB. We evaluated the diagnostic accuracy of this pattern, and prospectively validated our results.

METHODS

The retrospective cohort included 158 patients with angina who underwent both SE and coronary CT angiography (CCTA). The validation cohort included 37 patients who underwent CCTA in the emergency department for angina, and prospectively underwent SE. CCTA was used as a reference standard for the presence/absence of an MB, and also confirmed no obstructive CAD.

RESULTS

In the retrospective cohort, an MB was present in 107 (67.7%). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 91.6%, 70.6%, 86.7% and 80%, respectively. On logistic regression, focal septal buckling and Duke treadmill score were associated with an MB. In the validation cohort, an MB was present in 31 (84%). The sensitivity, specificity PPV and NPV were 90.3%, 83.3%, 96.5% and 62.5%, respectively. On logistic regression, focal septal buckling was associated with an MB.

CONCLUSION

Presence of focal septal buckling with apical sparing on SE is an accurate predictor of an MB in patients with angina and no obstructive CAD. This pattern can reliably be used to screen patients who may benefit from advanced non-invasive/invasive testing for an MB as a cause of their angina.

Surgical Unroofing of Hemodynamically Significant Left Anterior Descending Myocardial Bridges

BACKGROUND

Left anterior descending artery myocardial bridges (MBs) range from clinically insignificant incidental angiographic findings to a potential cause of sudden cardiac death. Within this spectrum, a group of patients with isolated, symptomatic, and hemodynamically significant MBs despite maximally tolerated medical therapy exist for whom the optimal treatment is controversial. We evaluated supraarterial myotomy, or surgical unroofing, of the left anterior descending MBs as an isolated procedure in these patients.

METHODS

In 50 adult patients, we prospectively evaluated baseline clinical characteristics, risk factors, and medications for coronary artery disease, relevant diagnostic data (stress echocardiography, computed tomography angiography, stress coronary angiogram with dobutamine challenge for measurement of diastolic fractional flow reserve, and intravascular ultrasonography), and anginal symptoms using the Seattle Angina Questionnaire. These patients then underwent surgical unroofing of their left anterior descending artery MBs followed by readministration of the Seattle Angina Questionnaire at 6.6-month (range, 2 to 13) follow-up after surgery.

RESULTS

Dramatic improvements were noted in physical limitation due to angina (52.0 versus 87.1, p < 0.001), anginal stability (29.6 versus 66.4, p < 0.001), anginal frequency (52.1 versus 84.7, p < 0.001), treatment satisfaction (76.1 versus 93.9, p < 0.001), and quality of life (25.0 versus 78.9, p < 0.001), all five dimensions of the Seattle Angina Questionnaire. There were no major complications or deaths.

CONCLUSIONS

Surgical unroofing of carefully selected patients with MBs can be performed safely as an independent procedure with significant improvement in symptoms postoperatively. It is the optimal treatment for isolated, symptomatic, and hemodynamically significant MBs resistant to maximally tolerated medical therapy.